In the medical field, personnel are often required to work in close proximity to patients undergoing imaging procedures involving x-rays, commonly referred to as fluoroscopy. The hazard to the worker arises from x-rays scattered by the patient's body toward the worker. Although such scattered radiation has a lower energy level than the direct x-ray beam, it does maintain its ionizing potential. Exposure to this scattered radiation has the potential to produce a significant radiation hazard over the working lifetime of the worker. For this reason, workers traditionally wear a radiation shielding garment that places a protective barrier between the scattering tissues of the patient and the body of the worker.
Traditionally such garments are made from a flexible rubber or polymer material within which is embedded powdered lead, a good absorber of x-rays. Unfortunately, lead garments are heavy and can cause significant injury to the wearer with daily use over a working lifetime. There has thus begun a search for lighter weight materials which can provide equivalent protection under the conditions of this job.
An underlying principle of such reduced weight garments is that for a large portion of the x-ray energy levels commonly used in medical procedures, certain elements, provide greater attenuation per unit weight than lead. Until now, most workers have assumed that the testing of the effectiveness of such elements other than lead requires meeting the requirements of shielding from the effects of the direct x-ray beam from the x-ray source.
It is now realized, however, that the danger to the worker is primarily caused by radiation reflected from the patient's body, so-called “scattered radiation”. An additional problem, however, arises from the fact that many of these lower atomic number heavy metals reradiate the x-rays they absorb, albeit at lower energy levels. This can lead to a problem where the exposure to the wearer is greater than that evident from the attenuation tests.